1. Field of the Invention
The present invention is generally related to an operation of an alternator associated with the marine propulsion system and, more particularly, to a method for controlling the alternator in such a way that it does not decrease the power that can be provided by an internal combustion engine during certain modes of operation of a marine vessel.
2. Description of the Prior Art
Those skilled in the art of marine propulsion engines and electrical systems used with those engines are familiar with many types of alternators and associated circuits.
U.S. Pat. No. 4,111,174, which issued to Fitzner et al on Sep. 5, 1978, discloses an ignition system with an idle speed governor apparatus. An alternator driven capacitive discharge ignition system includes a tachometer circuit monitoring the speed-dependent repetition rate of discharge at an internal trigger power supply, the tachometer circuit causing the triggering threshold bias to be reduced below idle speed to electronically advance the timing. The ignition circuit includes a triggering threshold bias capacitor in series with the trigger pulse source and the trigger power supply having a pilot capacitor to alternately fire a pair of ignition silicon controlled rectifiers.
U.S. Pat. No. 6,342,775, which issued to Sleder, Sr. on Jan. 29, 2002, discloses an automatic battery switching circuit for a marine propulsion system. A battery switching circuit provides a mechanism by which a plurality of electrical storage batteries can be alternatively connected in parallel or series based on the position of a manually controlled joystick of a marine positioning and maneuvering system. When the joystick is in a neutral position in which no docking motion is demanded by the marine vessel operator, the storage batteries are connected in parallel so they can benefit by charging by an alternator or generator associated with an internal combustion engine. If the joystick is moved out of its neutral position, the batteries are immediately connected in series to provide power to a plurality of electric motors that are used to drive a plurality of impellers of the docking system.
U.S. Pat. No. 4,325,350, which issued to Bauer et al on Apr. 20, 1982, discloses an alternator-powered breakerless capacitor discharge ignition system having improved low-speed timing characteristics. An alternator-powered breakerless capacitor discharge ignition system for an alternate firing two-cylinder outboard motor provides improved timing characteristics at low, as well as high, engine speeds and prevents reverse engine rotation. The alternator rotor and stator assemblies define a first magnetic circuit which provides constant polarity, constant power pulses for charging a single capacitor in the system. The alternator rotor and trigger assemblies define a second magnetic circuit which provides synchronized narrow trigger pulses, successive ones of the trigger pulses being of opposite polarity, to operate an electronic control circuit to effect timed capacitor discharge to a pair of spark plug ignition coils in the system.
U.S. Pat. No. 6,280,269, which issued to Gaynor on Aug. 28, 2001, discloses an operator display panel control by throttle mechanism switch manipulation. A throttle control mechanism is provided with a plurality of buttons and a control unit that interprets the state of the various buttons and switches in different ways, depending on the state of a first operating parameter. The first operating parameter can be the gear selector position or the status of a manual selector switch or push button. Based on the state of the first operating parameter, at least one switch is interpreted to represent a first command based on a first state of the first operating parameter and a second command based on the second state of the first operating parameter. This allows dual functionality for the buttons and switches which reduces the required number of switches and also allows the important control switches to be placed easily within reach of the operator of a marine vessel.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
It is well known to use alternators in conjunction with an engine of a marine propulsion system in order to charge electrical storage batteries used as an electrical power source for the operation of the engine and associated equipment relating to the operation of the marine vessel. Under certain circumstances of operation, such as during a rapid acceleration from a standing position, maximum power is required from the engine in order to achieve the required acceleration rate necessary to rapidly accelerate the boat from a standing position to an on-plane operating condition. Since the alternator requires mechanical power provided by the engine, the engine is unable to provide as much of its total power to the function of propelling a marine vessel as could otherwise be possibly if the alternator loads were removed.
In a typical marine system, a belt driven alternator is provided to convert rotational mechanical energy, provided by the crankshaft of the engine, into electrical energy which is used to charge the batteries of the marine propulsion system. Unlike alternators normally used in automotive applications, marine alternators are small, compact, and generally incapable of supplying all of the energy necessary to accommodate large power, short duration, electrical loads such as the trimming operation used to change the attitude of a marine propulsion system relative to its marine vessel. As a result, many outboard motor manufacturers now specify a large ampere-hour battery which, when called upon, can safely and effectively supply the necessary energy to satisfy these types of conditions. Once the load, such as a trimming event, is removed from the system, the alternator can replenish the battery charge to its proper state in a reasonable amount of time without detracting from engine operating performance.
The sudden acceleration from a standing position of a marine vessel to an on-plane condition is a scenario that occurs frequently in certain marine vessel applications. The engine usually begins fully trimmed under, with the propeller moved forward to its closest position relative to the transom of the marine vessel, with the transmission in forward gear and the engine operating at idle speed immediately prior to the sudden acceleration. Upon initiation of a rapid acceleration event, the operator of the marine vessel commands maximum engine acceleration which corresponds to a wide open throttle (WOT) condition. As the engine is accelerating, the operator of the marine vessel is often trimming the engine upward to move the propeller rearwardly relative to the transom in order to achieve boat lift and to obtain maximum speed as quickly as possible. During this combination of acceleration and trimming, as much as 100 amperes of current can be required to run the trim pump under the rapidly accelerating marine vessel conditions. This often exceeds the capability of the small alternator's output and the battery's power is used to satisfy the balance of this electrical requirement.
Depending on the condition of the battery, it is often possible to rely solely on the battery to produce all electrical demands during this acceleration and trimming maneuver. However, the alternator continues to require mechanical power from the engine in known marine propulsion systems. The power required to turn the alternator, when it is activated, could be advantageously used to enhance the acceleration time of the marine vessel if that power could alternatively by provided to the propeller.
In known marine propulsion systems, the alternator's field current is controlled by a voltage regulation circuit that is not sensitive to engine dynamic conditions. If an additional electrical load is applied to the system, the alternator will immediately react to this load and attempt to supply the electrical demand. This, in turn, provides an additional load on the engine which deprives the engine from the ability from providing maximum power to the propeller shaft in order to achieve the required acceleration in a minimum time.
It would therefore be significantly beneficial if a system could be provided by which the load on the engine caused by the alternator could be temporally removed during certain rapid acceleration and trimming maneuvers.